The <i>Arabidopsis HY2</i> Gene Acts as a Positive Regulator of NaCl Signaling during Seed Germination

• Main Authors: Mingxin Piao, Jinpeng Zou, Zhifang Li, Junchuan Zhang, Liang Yang, Nan Yao, Yuhong Li, Yaxing Li, Haohao Tang, Li Zhang, Deguang Yang, Zhenming Yang, Xinglin Du, Zecheng Zuo
• Format: Article
• Language: English
• Published: MDPI AG 2021-08-01
• Series: International Journal of Molecular Sciences
• Subjects: <i>Arabidopsis</i>; <i>HY2</i>; salt stress; seed germination; proteome; DRPs
• Online Access: https://www.mdpi.com/1422-0067/22/16/9009
• ISSN: 1661-6596; 1422-0067

Phytochromobilin (PΦB) participates in the regulation of plant growth and development as an important synthetase of photoreceptor phytochromes (phy). In addition, <i>Arabidopsis</i> long hypocotyl 2 (HY2) appropriately works as a key PΦB synthetase. However, whether <i>HY2</i> takes part in the plant stress response signal network remains unknown. Here, we described the function of HY2 in NaCl signaling. The <i>hy2</i> mutant was NaCl-insensitive, whereas HY2-overexpressing lines showed NaCl-hypersensitive phenotypes during seed germination. The exogenous NaCl induced the transcription and the protein level of <i>HY2</i>, which positively mediated the expression of downstream stress-related genes of <i>RD29A</i>, <i>RD29B</i>, and <i>DREB2A</i>. Further quantitative proteomics showed the patterns of 7391 proteins under salt stress. HY2 was then found to specifically mediate 215 differentially regulated proteins (DRPs), which, according to GO enrichment analysis, were mainly involved in ion homeostasis, flavonoid biosynthetic and metabolic pathways, hormone response (SA, JA, ABA, ethylene), the reactive oxygen species (ROS) metabolic pathway, photosynthesis, and detoxification pathways to respond to salt stress. More importantly, ANNAT1–ANNAT2–ANNAT3–ANNAT4 and GSTU19–GSTF10–RPL5A–RPL5B–AT2G32060, two protein interaction networks specifically regulated by HY2, jointly participated in the salt stress response. These results direct the pathway of <i>HY2</i> participating in salt stress, and provide new insights for the plant to resist salt stress.